Extraction of ketones



Nov. 8, 1949 A. GATHMAN ET AL EXTRACTION OF KETONES Filed Dec. 29, 1944 CCNDENSER.

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EXTRACTION OF KETONES Albert Gathman, Elizabeth, and Raymond W. Egberts, Roselle, N. J., assignors to Standard Oil Development Company, a corporation of Delaware Application December 29, 1944, Serial No. 570,450

2 Claims. (Cl. 260-593) This invention relates 'to the separation of ketones from industrial solvent mixtures, and in particular to the separationoi the lower ketones from recovery systems.

The removal of impurities often presents particular problems in processing for the preparation and recovery of many industrial liquids. A method commonly employed for the purication of organic liquids, especially as to the removal of water, is azeotropic distillation in the presence of added entrainer compounds. Such processing is usuallyl advantageous only when the distillate material contains a low content of the desired liquid land there is 4thus obtained as distillation residue a' high percentage yield of pure liquid. Poorphase separation Ain .the distillate material and contamination of the distillation residue due to. difcultly removable impurities often determine the unsuitability of such processing. The present invention is concerned with the purification of ketones from crude mixtures as commonly available involving solvent extraction methods considerably more advantageous than that of azeotropic distillation as presently generally applied. y

yThe separation of ketones from mixtures of alcohols and water isnot satisfactorily accomplished by the fractional distillation processes. The unsuitability of distillation procedure is due to the formation of binary and ternary azeotropes by the ketone with the alcohols and water, thus involving low percentage recovery of the desired ketones. The use of entrainers such as hexane and benzene does not contribute to more satisfactory operation on account of the formation of other azeotropic compositions. This invention relates to the use, as extractive media for the ketones. of high boiling hydrocarbons which do not form azeotropic mixtures with any of the constituents of the crude ketone mixtures and thus to obtain the ketone in relatively high degree of purity-after the removal of the solvent.

It has `been found that when a crude ketone mixture, such as a used solvent mixture from the artificial leather industry, is contacted with a higher boiling hydrocarbon material such as a mineral white oil of viscosity from 1 to 40 centipoises in volumes of fractional portions to about equal volumes, two liquid phases are formed, and that in the upper layer the ketone and mineral oil predominantly occur while the lower layer contains largely water and the difllcultly removable water-soluble impurities such as the alcohols. This treatment may be made satisfactorily either by batch operation or in continuous countercur- 2 rent manner. The extract solution in either case is subjected to distillation, and the distillate further puried by fractional distillation. In this manner upon a continuous basis, recovery of ketones almost to the extent of 100% has been found to occur from such complex crude ketone mixtures as the recovered solvent of the articial leather industry. By batch processing, 90% of methyl ethyl ketone has been removed from a mixture containing 66.7% of ketone in ethyl alcohol and water.

The hydrocarbon extractant employed according to the invention is preferably highly parafflnic in character, although naphthene and aromatic hydrocarbons of good chemical stability and boiling range substantially different from the ketone mixture may be advantageously employed. Usually a difference of at least F. from the final boiling point of the ketone mixture is necessary for advantageousvprocessing. Due to their stability, cheapness and availability, mineral white oils are commonly employed.

In order to present a fuller understanding of the invention, the following description is presented. The reference numerals have relation to the accompanying drawing in which a typical iiow diagram is presented as to processing car-.

ried out according to the invention on a continuous scale.

Into a countercurrent extraction tower I0, the used ketone solvent mixture from the artificial leather industry, containing mainly methyl ethyl ketone, ethyl alcohol and Water, was passed under atmospheric conditions through line I 2, While a mineral oil of 1.6 centipoises and of boiling range from 403 F. to 500 F. was passed through line I 4. To provide for crude mixtures having too low water contents to permit advantageous diphase separation in the tower, water may be added through line I6 as required to supply such .deficiency Through line I8 is thus obtained a stream containing mainly oil and methyl ethyl ketone and minor amounts of ethyl alcohol. This stream is passed to the distillation tower 20. Overhead from the tower 20 through line 22 a stream of composition approximately that of the ternary azeotrope of methyl ethyl ketone, ethyl alcohol and water is obtained and passed to the condenser 24. A portion of the condensate is returned to the tower 20 as reflux through the line 26 while the remainder passes through the line 28 into the crude supply line I2. As distillation residue from the tower 2o is separated, through line 30, a concentrated solution of methyl ethyl ketone in mineral oil solution.

, 3 The methyl ethyl ketone solution passing through line 30 is passed to the distillation tower 32 wherein separation is eiected of highly purified methyl ethyl ketone from the oil solvent. l

The ketone is passed through line 34 into the condenser 36 and then partly as reflux through line 33 to `the 'tower 32; while ithe. remainder is, passed to storage through "line 40.

The residue in the tower I consists largely of the water, ethyl alcohol and water-soluble.

ing water-soluble impurities ,astesidual. material.

passed through line 56 tov an alcohol recovery system. The overhead stream passes "through line 54 to the condenser 158 and thence, partly as reflux through line .60 to the .tower 52, .andfpar-tly through .line 62 into'thefcrude .feed supply line I 2,.

.-Fro'm the base of, the tower 32 thereis obtained solvent oil for .recycling through .line 64 after cooling .in .equipment -l' and passage into. the oil supply line, 'M for the-.towerl 0.

The processing laccording to the, invention is particularly .signi-izant .in connection with the. recovery of ketones from used solvent mixtures of Ehe artiiieial leather industry. In, the prepa ration of articial leather, mixtures :0i-solvents, usuallyI ketones, alcohols., acetates and hydrocarbons, :are fused. .After use,l the .solvent'mixture is :generally recoyeredweither by absorption on charcoal or by water washing. `'llsie distillation of fthe -recovered mixture .results inthe formation of. za ternary fblend of, :for exam-ple, methyl `ethyl ketone, ethyl :alcohol and water. Similarly, in many manufacturing lprocedures, ternary mixtures `'involving lthe lower ketones as 'constituents are oftenfobtained. Processing according to this invention iis :advantageous for fthe recovery =of many industrial-ly important fketones, including acetone, lfrom lliquors obtained in the. preparation of (other compounds @and of 'the used liquids of industrial processes, particularly they .artificial leather-industry.

Whatlisclaimedfis:

1. The process of separating the constituents of a crude mixture yconsisting :essentially Hof methyl ethyl ketone, ethyl alcohol, and water, which comprises countercurrently contacting said crude mixture with a higher boiling petroleum distillate oil having a boiling range from 403 F. to 500 F. ln an amount eiecting diphase treatment, distilling the substantially oil phase to produce za distillate 'iraction contain mainly :alcohol and lwater-andra fresiduafllllradtion dcontaining said petroleum distillate oil and methyl ethyl ketone, mecyoling said distillate fraction to said counter- .currentoil contacting and redistilling said residual 'fraction to recover highly puried methyl v `ethyltaiwanais @distillate fraction.

42 Ehe process' of separating methyl ethyl ilcetonefirom 'a emile mixture consisting essentially of methyl ethyl ketone, ethyl alcohol and water, Whiohcomprises countercurrently contacting said crude mixture with a petroleum distillate oilmomposed of higher boiling hydrocarbons havf ing a boiling point at least '15 F. above that of the .ketone .riiixtu-re,l which do not. .form ansotropic, mixtures with any oi .constituents-,Qi said. crude mixture. .and .an amount enacting diphase treatment, distilling trom resulting oil ,phase alcohol andmater extracted fthe oil phas tofproduoea -idistlllatn ration contain* ing mainly alcohol-and vwater, a residual fraction tcontaining said petroleum all and. methyl ethyl .keizerin recycling said distillate fraction. .to .said `cour-item:urren't oil contacting. and .redistilling said residual traction to renover highly purified methyl ketone distillate .fractie n.

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The following references are fof; xrecord vriler fof @atei-it.-

OTHER REEEaENcos Gthmem 1nd. Eng. Chem., Bagages '10H05 

